Showcase of Immutables and Guice for typed id generation

Sample.java

package abc;

import com.google.inject.Injector;
import com.google.inject.Guice;
import javax.inject.Inject;
import javax.inject.Provider;
import com.google.inject.AbstractModule;
import com.google.inject.Provides;
import org.immutables.value.Value;
import org.immutables.value.Value.Style.ImplementationVisibility;

// You can place styles on package or classes or as meta
// annotations, as described in documentation (immutables.github.io/style.html)
@Value.Style(
		typeAbstract = "_*",
		typeImmutable = "*",
		visibility = ImplementationVisibility.PUBLIC,
		defaults = @Value.Immutable(builder = false, copy = false))
public class Sample {

	// There's no real need in this super-type,
	// But I usually use something like that when I have
	// a lot of similar IDs or wrapper types.
	abstract static class BaseId<T> {
		@Value.Parameter
		abstract T value();

		@Override
		public String toString() {
			return value().toString();
		}
	}

	// using "reverse" style, StringId class will be
	// generated from _StringId abstract value type
	@Value.Immutable
	abstract static class _StringId extends BaseId<String> {}

	@Value.Immutable
	abstract static class _LongId extends BaseId<Long> {}

	interface IdGenerator {

		long newId();
	}

	// First option is to use module
	static class IdModule extends AbstractModule {
		@Override
		protected void configure() {}

		@Provides
		public StringId stringId(IdGenerator generator) {
			return StringId.of("id_" + generator.newId());
		}
		@Provides
		public LongId longId(IdGenerator generator) {
			return LongId.of(generator.newId());
		}
	}

	// Second option is to use provider
	static class StringIdProvider implements Provider<StringId> {
		@Inject
		IdGenerator generator;

		@Override
		public StringId get() {
			return StringId.of("id_" + generator.newId());
		}
	}

	static class StringIdUser {
		@Inject
		StringId id;
	}

	static class Gen implements IdGenerator {
		@Override
		public long newId() {
			return System.currentTimeMillis();
		}
	}

	public static void main(String... args) {

		Injector usingModule = Guice.createInjector(new AbstractModule() {
			@Override
			protected void configure() {
				install(new IdModule());
				bind(IdGenerator.class).to(Gen.class);
			}
		});

		StringIdUser user = usingModule.getInstance(StringIdUser.class);
		System.out.println(user.id);

		Injector usingProvider = Guice.createInjector(new AbstractModule() {
			@Override
			protected void configure() {
				bind(IdGenerator.class).to(Gen.class);
				bind(StringId.class).toProvider(StringIdProvider.class);
			}
		});

		user = usingProvider.getInstance(StringIdUser.class);
		System.out.println(user.id);
	}
}